is it mandatory for people who have already gone through the orientation speech, signed up, etc?

No general meetings are mandatory for all staff in general, but there may be training or planned meetups with certain groups of staff at particular meetings, which will be communicated to the particular staff in advance, or announced in the meeting announcements.

Also, staff are strongly encouraged to attend the last two meetings before the convention as these have the most news and information.

Will the minutes be available somewhere? I can't attend yet again, because I won't even be in the contiguous states that weekend. And I feel really bad because this will be the third meeting I will have missed in a row.